Light-emitting device and method for manufacturing the same

ABSTRACT

The present invention provides a display device and a manufacturing method thereof that can simplify manufacturing steps and enhance efficiency in the use of materials, and further, a manufacturing method that can enhance adhesiveness of a pattern. One feature of the invention is that at least one or more patterns needed for manufacturing a display panel, such as a conductive layer forming a wiring or an electrode or a mask for forming a desired pattern is/are formed by a method capable of selectively forming a pattern, thereby manufacturing a display panel.

TECHNICAL FIELD

The present invention relates to a light-emitting device including anactive element such as a transistor formed over a large-size glasssubstrate and to a method for manufacturing the same.

BACKGROUND ART

Conventionally, a display panel of a so-called active matrix drivingsystem constituted by a thin film transistor (hereinafter also referredto as a “TFT”) over a glass substrate is known. This active matrixdisplay panel is manufactured by patterning various thin films by alight-exposure step using a photomask, similarly to a manufacturingtechnique of a semiconductor integrated circuit.

Until now, there is employed a manufacturing method for cutting outplural display panels from one mother glass substrate and mass-producingefficiently. The size of a mother glass substrate used for manufacturingdisplay panels is increased from 300 mm×400 mm of the first generationin the early 1990s to 680 mm×880 mm or 730 mm×920 mm of the fourthgeneration in 2000. Furthermore, the manufacturing method has beendeveloped so that a large number of display panels can be obtained fromone substrate.

When a size of a glass substrate or a display panel is small, apatterning treatment can be carried out comparatively easily by using aphotolithography apparatus. However, as a substrate size is increased,an entire surface of a display panel cannot be simultaneously treated bycarrying out a light-exposure treatment once. Consequently, a method forexposing an entire surface of a substrate to light has been developed asa light-exposure treatment. (for example, consecutive light-exposure toone substrate for connecting edges of elements such as a wiring not tobe disconnected at a boundary between the elements). This method isperformed by dividing a region where a photoresist is applied into aplurality of block regions, carrying out a light-exposure treatment onevery predetermined block regions, and by sequentially repeating them(for example, Reference 1: Japanese Patent Laid-Open No. Hei 11-326951).

DISCLOSURE OF INVENTION

However, a glass substrate is further enlarged to a size of 1000 mm×1200mm or 1100 mm×1300 mm in the fifth generation, and a size of 1500mm×1800 mm or more is assumed in the next generation. However, it isdifficult to manufacture a display panel with good productivity and alow cost by a conventional patterning method. In other words, when aplurality of times of light-exposure treatment is carried out by theabove-described consecutive light-exposure, a processing time isincreased. Tremendous investment is required for developing aphotolithography apparatus that can treat a large-sized glass substrate.

Moreover, there is a problem that a material cost is wasted and disposalof a large quantity of effluent is forced in a method for formingvarious types of thin films over an entire surface of a substrate andfor removing the thin films to leave a slight region by etching,

The invention has been made in view of such a problem. It is an objectof the invention is to provide a light-emitting device by whichefficiency in the use of a material can be improved and a manufacturingstep can be simplified, and a manufacturing method thereof.

According to one aspect of the invention, at least one or more patternsneeded for manufacturing a display panel, such as a conductive layerforming a wiring or an electrode or a mask for forming a desired patternis/are formed by a method capable of selectively forming a pattern,thereby manufacturing a display panel. There is employed a dropletdischarging method (referred to as an ink-jetting method depending onthe system) that can form a conductive layer or an insulating layer anda desired pattern by selectively discharging droplets having acomposition prepared for a particular object as the method capable ofselectively forming a pattern.

A display device can be formed by using a droplet discharging method. Inthe display device, a TFT is connected to a light-emitting element, inwhich an organic material or a medium containing a mixture of an organicmaterial and an inorganic material that generates light-emission, thatis, electroluminescence (referred to as an EL) is disposed betweenelectrodes according to one aspect of the invention.

A light-emitting device according to one aspect of the invention,comprises at least a first thin film transistor and a second thin filmtransistor in every pixel. The first thin film transistor and the secondthin film transistor comprises a gate electrode containing a conductivematerial; a gate insulating layer formed over the gate electrode; asemiconductor film formed over the gate insulating layer; and a sourcewiring and a drain wiring formed over the semiconductor film. In thelight-emitting device, one of the source wiring and the drain wiring ofthe first thin film transistor is connected to the gate electrode of thesecond thin film transistor, and the semiconductor film does notprotrude from (does not extend beyond) an edge of the gate insulatinglayer.

A light-emitting device according to one aspect of the invention,comprises at least a first thin film transistor and a second thin filmtransistor in every pixel. The first thin film transistor and the secondthin film transistor comprises a gate electrode containing a conductivematerial; a gate insulating layer formed over the gate electrode; asemiconductor film formed over the gate insulating layer; and a sourcewiring and a drain wiring formed over the semiconductor film. In thelight-emitting device, one of the source wiring and the drain wiring ofthe first thin film transistor is connected to the gate electrode of thesecond thin film transistor, and an edge of the semiconductor film isaligned with an edge of the gate insulating layer.

A light-emitting device according to one aspect of the invention,comprises at least a switching thin film transistor and a driving thinfilm transistor in every pixel. The switching thin film transistorincludes a first gate electrode made of a conductive material; a firstisland-like gate insulating layer in contact with the first gateelectrode; a first island-like semiconductor film in contact with thefirst gate insulating layer; a second semiconductor film including oneconductivity type impurity in contact with the first semiconductorlayer; and a source wiring and a drain wiring in contact with the secondsemiconductor film including one conductivity type impurity; and thedriving thin film transistor includes a second gate electrode made ofthe conductive material; a second island-like gate insulating layer incontact with the second gate electrode; and a third island-likesemiconductor film in contact with the second gate insulating layer. Inthe light-emitting device, a portion of the second gate electrode isexposed, a source wiring and a drain wiring of the switching thin filmtransistor is connected to the gate electrode of the driving thin filmtransistor, and an edge of the first semiconductor film or the thirdsemiconductor film of the switching thin film transistor and the drivingthin film transistor does not protrude from an edge of the first gateinsulating layer or the second gate insulating layer.

A light-emitting device according to one aspect of the invention,comprises at least a switching thin film transistor and a driving thinfilm transistor in every pixel. The switching thin film transistorcomprises a first gate electrode made of a conductive material; a firstisland-like gate insulating layer in contact with the first gateelectrode; a first island-like semiconductor film in contact with thefirst gate insulating layer; a second semiconductor film including oneconductivity type impurity in contact with the first semiconductorlayer; a source wiring and a drain wiring in contact with the secondsemiconductor film including one conductivity type impurity; and thedriving thin film transistor comprises a second gate electrode made ofthe conductive material; a second island-like gate insulating layer incontact with the second gate electrode; a third island-likesemiconductor film in contact with the second gate insulating layer. Inthe light-emitting device, a portion of the second gate electrode isexposed, one of the source wiring and the drain wiring of the switchingthin film transistor is connected to the gate electrode of the drivingthin film transistor, and an edge of the first semiconductor film or thethird semiconductor film of the switching thin film transistor and thedriving thin film transistor is aligned to an edge of the first gateinsulating layer or the second gate insulating layer.

A light-emitting device according to one aspect of the invention,comprises at least a first thin film transistor and a second thin filmtransistor in every pixel. The first thin film transistor and the secondthin film transistor comprise a base film; a gate electrode containing aconductive material in contact with the base film; a gate insulatinglayer formed over the gate electrode; a semiconductor film formed overthe gate insulating layer; and a source wiring and a drain wiring formedover the semiconductor film. In the light-emitting device, one of thesource wiring and the drain wiring of the first thin film transistor isconnected to the gate electrode of the second thin film transistor, andan edge of the semiconductor film does not protrude from an edge of thegate insulating layer.

A light-emitting device according to one aspect of the invention,comprises a first thin film transistor and a second thin film transistorin every pixel. The first thin film transistor and the second thin filmtransistor comprise a base film; a gate electrode containing aconductive material in contact with the base film; a gate insulatinglayer formed over the gate electrode; a semiconductor film formed overthe gate insulating layer; and a source wiring and the drain wiringformed over the semiconductor film. In the light-emitting device, one ofthe source wiring and the drain wiring of the first thin film transistoris connected to the gate electrode of the second thin film transistor,and an edge of the semiconductor film is aligned to an edge of the gateinsulating layer.

A light-emitting device according to one aspect of the invention,comprises a switching thin film transistor and a driving thin filmtransistor in every pixel. The switching thin film transistor comprisesa base film; a first gate electrode made of a conductive material incontact with the base film; a first island-like gate insulating layer incontact with the first gate electrode; a first island-like semiconductorfilm in contact with the first gate insulating layer; a secondsemiconductor film including one conductivity type impurity in contactwith the first semiconductor layer; a source wiring and a drain wiringin contact with the second semiconductor film including one conductivitytype impurity; and the driving thin film transistor comprises a basefilm; a second gate electrode made of the conductive material in contactwith the base film; a second island-like gate insulating layer incontact with the second gate electrode; a third island-likesemiconductor film in contact with the second gate insulating layer. Inthe light-emitting device, a portion of the second gate electrode isexposed, one of the source wiring and the drain wiring of the switchingthin film transistor is connected to the gate electrode of the drivingthin film transistor, and an edge of the first semiconductor film or thethird semiconductor film of the switching thin film transistor and thedriving thin film transistor does not protrude from an edge of the firstgate insulating layer or the second gate insulating layer.

A light-emitting device according to one aspect of the invention,comprises a switching thin film transistor and a driving thin filmtransistor in every pixel. The switching thin film transistor comprisesa base film; a first gate electrode made of a conductive material incontact with the base film; a first island-like gate insulating layer incontact with the first gate electrode; a first island-like semiconductorfilm in contact with the first gate insulating layer; a secondsemiconductor film including one conductivity type impurity in contactwith the first semiconductor layer; and a source wiring and a drainwiring in contact with the second semiconductor film including oneconductivity type impurity; and the driving thin film transistorcomprises a base film; a second gate electrode made of the conductivematerial in contact with the base film; a second island-like gateinsulating layer in contact with the second gate electrode; and a thirdisland-like semiconductor film in contact with the second gateinsulating layer. In the light-emitting device, a portion of the secondgate electrode is exposed, one of the source wiring and the drain wiringof the switching thin film transistor is connected to the second gateelectrode of the driving thin film transistor, and an edge of the firstsemiconductor film or the third semiconductor film of the switching thinfilm transistor and the driving thin film transistor is aligned to anedge of the first gate insulating layer or the second gate insulatinglayer.

In the light-emitting device according to one aspect of the invention, aprotective film is formed over the semiconductor film, the firstsemiconductor film, or the third semiconductor film.

A method of manufacturing a light-emitting device, according to oneaspect of the invention, comprises the respective steps; forming a gateelectrode by a droplet discharging method over a substrate having aninsulating surface or a substrate having a base surface that is exposedto a pretreatment; forming a gate insulating layer and a semiconductorfilm over the gate electrode; forming a first mask by a dropletdischarging method over the semiconductor film; etching thesemiconductor film the and gate insulating layer continuously with thefirst mask; removing the first mask; forming a protective layer over thesemiconductor film; forming a semiconductor film including oneconductivity type impurity; forming a source wiring and a drain wiringby a droplet discharging method; and etching the semiconductor filmincluding one conductivity type impurity over the protective layer bythe source and drain wiring as a second mask.

A method of manufacturing a light-emitting device having a switchingthin film transistor and a driving thin film transistor in every pixel,according to one aspect of the invention, comprises the respective stepsof: forming a gate electrode of a switching thin film transistor and agate electrode of a driving thin film transistor by a dropletdischarging method over a substrate having an insulating surface or asubstrate having a base surface that is exposed to a pretreatment;forming a gate insulating layer and a semiconductor film over the gateelectrode of the switching thin film transistor and the gate electrodeof the driving thin film transistor; forming a first mask by a dropletdischarging method over the semiconductor film; etching thesemiconductor film and the gate insulating layer continuously with thefirst mask to expose a portion of the gate electrode of the driving thinfilm transistor; removing the first mask; forming a protective layerover the semiconductor film; forming a semiconductor film including oneconductivity type impurity; forming a source wiring and a drain wiringby a droplet discharging method, at the same time, and connecting atleast one of the source wiring and the drain wiring to the gateelectrode of the driving thin film transistor; and etching thesemiconductor film including one conductivity type impurity over theprotective layer by the source wiring and the drain wiring as a secondmask.

The step of forming the gate insulating layer and the semiconductor filmover the gate electrodes of the switching thin film transistor and thedriving thin film transistor is preferably performed continuously by avapor phase growth method using plasma (plasma CVD) or a sputteringmethod without being exposed to an air.

The gate insulating layer is formed by sequentially laminating a firstsilicon nitride film, a silicon oxide film and a second silicon nitridefilm. Thus, the gate insulating layer can prevent oxidation of a gateelectrode and form a favorable interface with a semiconductor film to beformed over the gate insulating layer.

As described above, a mask to be used in patterning a gate insulatinglayer and a semiconductor film is formed by a droplet dischargingmethod, and the semiconductor film and the gate insulating layer areetched continuously, according to one aspect of the invention.

A method of manufacturing a light-emitting device, according to oneaspect of the invention, comprises the respective steps of: forming agate electrode by a droplet discharging method over a substrate havingan insulating surface or a substrate having a base surface that isexposed to a pretreatment; forming a base film over the gate electrodeas a pretreatment; forming a gate insulating layer and a semiconductorfilm over the base film; forming a first mask by a droplet dischargingmethod over the semiconductor film; etching the semiconductor film andthe gate insulating layer continuously with the first mask; removing thefirst mask; forming a protective layer over the semiconductor film;forming a semiconductor film including one conductivity type impurity;forming a source wiring and a drain wiring by a droplet dischargingmethod; and etching the semiconductor film including one conductivitytype impurity over the protective layer by the source wiring and thedrain wiring as a second mask.

A method of manufacturing a light-emitting device having a switchingthin film transistor and a driving thin film transistor in every pixel,according to one aspect of the invention, comprises the respective stepsof: forming a gate electrode of a switching thin film transistor and agate electrode of a driving thin film transistor by a dropletdischarging method over a substrate having an insulating surface or asubstrate having a base surface that is exposed to a pretreatment;forming a base film over the gate electrode of the switching thin filmtransistor and the gate electrode of the driving thin film transistor asa pretreatment; forming a gate insulating layer and a semiconductor filmover the base film; forming a first mask by a droplet discharging methodover the semiconductor film; etching the semiconductor film and the gateinsulating layer continuously with the first mask to expose a portion ofthe gate electrode of the driving thin film transistor; removing thefirst mask; forming a protective layer over the semiconductor film;forming a semiconductor film including one conductivity type impurity;forming a source wiring and a drain wiring by a droplet dischargingmethod, at the same time, and connecting at least one of the sourcewiring and the drain wiring to the gate electrode of the driving thinfilm transistor; and etching the semiconductor film including oneconductivity type impurity over the protective layer by the sourcewiring and the drain wiring as a second mask.

In the step of forming the gate insulating layer and the semiconductorfilm over the base film, it is preferable that the gate insulating layerand the semiconductor film are sequentially formed by a vapor phasegrowth method using plasma (plasma CVD) or a sputtering method withoutbeing exposed to the atmosphere.

The gate insulating layer is formed by sequentially laminating a firstsilicon nitride film and a silicon oxide film and a second siliconnitride film. Thus, the gate insulating layer can prevent oxidation of agate electrode and form a favorable interface with a semiconductor filmto be formed over the gate insulating layer.

As described above, a mask to be used in patterning a gate insulatinglayer and a semiconductor film is formed by a droplet dischargingmethod, and the semiconductor film and the gate insulating layer areetched continuously.

According to the present invention, a gate electrode and a wiring isformed by a droplet discharging method, and Ag or Cu can be used for theconductive material. Also, an alloy containing Ag or Cu or a laminationof Ag and Cu can be also used. A silicon nitride film or a siliconoxynitride film is formed to be contact with a top surface of the gateelectrode or the wiring, thereby preventing deterioration due tooxidation. Au, W, or Al may be used as the conductive material.

In the invention, the semiconductor film, which is a main portion of aTFT, can be also formed from a semi-amorphous semiconductor containinghydrogen and halogen, and having a crystal structure. Accordingly, adriver circuit only including an n-channel type thin film transistor canbe provided. In other words, it is possible to form a driver circuitover one substrate by using a TFT in which a semiconductor containinghydrogen and halogen, and having a crystal structure is used as asemiconductor film and which can operate with an electric field effectmobility of 1 to 15 cm²/V-sec cm².

According to one aspect of the invention, patterning of a wiring or amask can be carried out directly by a droplet discharging method.Therefore, a thin film transistor by which efficiency in the use of amaterial is improved and a manufacturing step is simplified, and adisplay device using the thin film transistor can be obtained.

It is necessary that an active matrix system used for an EL displaypanel has a function of selecting a particular pixel and providing anecessary display information and a function of flowing current to alight-emitting element during one frame period. A driving thin filmtransistor for supplying current to a light-emitting element and aswitching thin film transistor are required for achieving the twofunctions simultaneously. A contact portion is needed, since theswitching thin film transistor should be connected to the driving thinfilm transistor electrically. According to the invention, a mask to beused in patterning the gate insulating layer and the semiconductor filmis formed by a droplet discharging method, and the semiconductor filmand the gate insulating layer are etched continuously. Thus, a gateelectrode of the driving thin film transistor is exposed and can beeasily have a contact with a source and drain wiring of the switchingthin film transistor.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIG. 1 is a top view showing a configuration of an EL display panelaccording to one aspect of the present invention;

FIG. 2 is a top view showing a configuration of an EL display panelaccording to one aspect of the present invention;

FIG. 3 is a top view showing a configuration of an EL display panelaccording to one aspect of the present invention;

FIGS. 4A to 4C are cross-sectional views each showing a manufacturingstep of an EL display panel according to one aspect of the presentinvention;

FIGS. 5A to 5C are cross-sectional views each showing a manufacturingstep of an EL display panel according to one aspect of the presentinvention;

FIGS. 6A to 6E are cross-sectional views each showing a manufacturingstep of an EL display panel according to one aspect of the presentinvention;

FIG. 7 is a cross-sectional view showing a manufacturing step of an ELdisplay panel according to one aspect of the present invention;

FIG. 8 is a top view showing a manufacturing step of an EL display panelaccording to one aspect of the present invention;

FIGS. 9A to 9D are cross-sectional views each showing a manufacturingstep of an EL display panel according to one aspect of the presentinvention;

FIGS. 10A to 10C are cross-sectional views each showing a manufacturingstep of an EL display panel according to one aspect of the presentinvention;

FIGS. 11A and 11B are cross-sectional views each showing a manufacturingstep of an EL display panel according to one aspect of the presentinvention;

FIG. 12 is a cross-sectional view showing a manufacturing step of an ELdisplay panel according to one aspect of the present invention;

FIG. 13 is a top view showing a manufacturing step of an EL displaypanel according to one aspect of the present invention;

FIG. 14 is a cross-sectional view showing a manufacturing step of an ELdisplay panel according to one aspect of the present invention;

FIG. 15 is a top view showing a liquid crystal display panel accordingto one aspect of the present invention;

FIG. 16 is an equivalent circuit diagram of the liquid-crystal displaypanel shown in FIG. 15;

FIGS. 17A and 17B each show a mode of a light-emitting element which canbe applied to the present invention;

FIGS. 18A and 18B each show a mode of a light-emitting element which canbe applied to the present invention;

FIGS. 19A and 19B each show a mounting method of a driver circuit of anEL display panel according to one aspect of the present invention;

FIGS. 20A and 20B each show a mounting method of a driver circuit of anEL display panel according to one aspect of the present invention;

FIGS. 21A to 21F are circuit diagrams each showing a configuration of apixel which can be applied to an EL display panel according to oneaspect of the present invention;

FIG. 22 shows a circuit configuration in the case of forming a scanningline driver circuit with a TFT in a liquid crystal display panelaccording to one aspect of the present invention;

FIG. 23 shows a circuit configuration in the case of forming a scanningline driver circuit with a TFT in a liquid crystal display panelaccording to one aspect of the present invention (a shift registercircuit);

FIG. 24 shows a circuit configuration in the case of forming a scanningline driver circuit with a TFT in a liquid crystal display panelaccording to one aspect of the present invention (a buffer circuit);

FIG. 25 shows a structure of a droplet discharging apparatus which canbe applied to the present invention;

FIG. 26 is a cross-sectional view showing in a configuration example ofan EL display module according to one aspect of the present invention;

FIG. 27 is a cross-sectional view showing in a configuration example ofan EL display module according to one aspect of the present invention;

FIG. 28 is a block diagram showing a main configuration of an EL TVreceiver according to one aspect of the present invention; and

FIG. 29 shows a structure of an EL TV receiver completed according toone aspect of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment modes of the present invention will be explained in detailwith reference to the drawings. Note that the same reference numeralsdenote the same parts among each drawing, and the explanation will notbe repeated in the following explanations. In addition, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art, unless such changes and modifications departfrom content and the scope of the invention. Therefore, the invention isnot interpreted with limiting to the description in the followingembodiment modes.

FIG. 1 shows a top view of a structure of an EL display panel accordingto the invention. A pixel portion 101 in which pixels 102 are arrangedin a matrix, a scanning line input terminal 103, and a signal line inputterminal 104 are formed on a substrate 100 having an insulating surface.The number of pixels may be provided according to various standards. Thenumber of pixels of XGA may be 1024×768×3 (RGB), the one of UXGA may be1600×1200×3 (RGB), and the one of a full-spec Hi-Vision(high-definition) may be 1920×1080×3 (RGB).

The pixels 102 are arranged in a matrix by intersecting a scanning lineextended from the scanning line input terminal 103 with a signal lineextended from the signal line input terminal 104. A thin film transistorfor controlling a connection state with the signal line (hereinafter,also referred to as a “switching thin film transistor” or a “switchingTFT”) and a thin film transistor for controlling current flowing into alight-emitting element (hereinafter, also referred to as a “driving thinfilm transistor” or a “driving TFT”) are provided for each of the pixels102, and the driving thin film transistor is connected in series to thelight-emitting element.

A TFT comprises a semiconductor film, a gate insulating layer, and agate electrode as the main components. A wiring connected to a sourceand drain region formed in the semiconductor film is included too. A topgate type in which a semiconductor film, a gate insulating layer, and agate electrode are arranged from a substrate side; a bottom gate type inwhich a gate electrode, a gate insulating layer, and a semiconductorfilm are arranged from a substrate side; and the like are known as astructure of a TFT. However, any one of structures may be applied to theinvention.

An amorphous semiconductor (hereinafter also refereed to as an “AS”)manufactured by using a semiconductor material gas typified by silane orgermane with a vapor phase growth method or a sputtering method; apolycrystalline semiconductor that is formed by crystallizing theamorphous semiconductor by utilizing light energy or thermal energy; asemi-amorphous semiconductor (also referred to as microcrystallite ormicrocrystal, and hereinafter also referred to as an “SAS”); and thelike can be used for a material to form a semiconductor film.

An SAS is a semiconductor with an intermediate structure between anamorphous and a crystal structure (including a single crystal and apolycrystal). This is a semiconductor having a third condition that isstable free-energetically, and a crystalline region having a short-rangeorder and lattice distortion is included therein. A crystalline regionof from 0.5 nm to 20 nm can be observed at least in a portion of aregion in the film. When silicon is contained as the main component,Raman spectrum is shifted to a lower wavenumber side less than 520 cm⁻¹.Diffraction peak of (111) or (220) to be caused from a crystal latticeof silicon is observed in X-ray diffraction. At least 1 atomic % or moreof hydrogen or halogen is contained as a neutralizer of a dangling bond.An SAS is formed by carrying out glow discharge decomposition (plasmaCVD) on a silicide gas. Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄, or the likecan be used for the silicide gas, in addition to SiH₄. In addition, GeF₄may be mixed. This silicide gas may be diluted with H₂ or H₂ and one ormore of the rare gas elements of He, Ar, Kr, and Ne. A dilution ratioranges from 2 times to 1000 times. A pressure ranges approximately from0.1 Pa to 133 Pa, and a power frequency ranges from 1 MHz to 120 MHz,preferably from 13 MHz to 60 MHz. A substrate heating temperature may be300° C. or less. It is desirable that an atmospheric constituentimpurity such as oxygen, nitrogen, or carbon is 1×10²⁰ atoms/cm³ or lessas an impurity element in the film, specifically an oxygen concentrationis 5×10¹⁹ atoms/cm³ or less, preferably 1×10¹⁹ atoms/cm³ or less.

FIG. 1 shows a structure of an EL display panel that controls a signalinputted into a scanning line and a signal line by an external drivercircuit. Furthermore, a driver ICs 105 and 106 may be mounted on asubstrate 100 by COG (Chip on Glass) as shown in FIG. 2. The driver ICsmay be formed on a single crystal semiconductor substrate or may beformed from a circuit with a TFT on a glass substrate.

When a TFT provided for a pixel is formed from an SAS, a scanning linedriver circuit 107 can be integrally formed on the substrate 100, asshown in FIG. 3. Reference numeral 108 denotes a protection diode.

FIG. 25 shows one mode of a droplet discharging apparatus used forforming patterns. Each head 1405 of a droplet discharge unit 1403 isindividually connected to a control unit 1407. A pattern that isprogrammed in advance can be drawn with a control of the control unit1407 using a computer 1410. The timing of drawing a pattern may bedecided based on a marker 1411 formed on a substrate 1400, for example.In addition, a reference point may be fixed with an edge of thesubstrate 1400 as a reference. A reference point is detected by animaging unit 1404 such as a CCD, and the computer 1410 recognizes adigital signal converted by an image processing unit 1409 to generate acontrol signal, and the control signal is transmitted to the controlunit 1407. Of course, information of a pattern to be formed on thesubstrate 1400 is placed in a recording medium 1408. Based on thisinformation, the control signal can be transmitted to the control unit1407, and thus, each head 1405 of the droplet discharging unit 1403 canbe controlled individually. Now, an apparatus that can discharge ametal, an organic material, and an inorganic material individually withone head, as discharging RGB respectively with one ink jet head like EL,has been developed. In the case of discharging an interlayer insulatingfilm widely, multiple thin lines may be drawn by using the same materialso as to enhance throughput. According to a droplet dischargingapparatus shown in FIG. 25, a length in which heads 1405 of the dropletdischarging unit 1403 are arranged is equal to a width of a substrate1400. However, the droplet discharging apparatus can form a pattern byrepeatedly scanning to a large size substrate having a broader widththan the length in which heads 1405 are arranged.

Next, a step of manufacturing an EL display panel using such a dropletdischarging apparatus is explained hereinafter.

Embodiment mode 1

A method for manufacturing a channel protective type TFT is explained inEmbodiment mode 1.

FIG. 4A shows a step of forming a gate electrode, and a gate wiringconnected to the gate electrode over a substrate 100 by a dropletdischarging method. Note that FIG. 4A shows a longitudinal sectionalstructure schematically, and FIG. 8 shows a planar structurecorresponding to a-b, c-d and e-f thereof, and thus, the figures can bereferred to at the same time.

A plastic substrate having the heat resistance that can withstandprocessing temperature of the manufacturing step, or other substratescan be used for the substrate 100, in addition to a non-alkaline glasssubstrate such as barium borosilicate glass, alumino borosilicate glass,or aluminosilicate glass manufactured with a fusion method or a floatingmethod, and a ceramic substrate. A semiconductor substrate such assingle crystal silicon, a substrate in which a surface of a metalsubstrate such as stainless is provided with an insulating layer may bealso employed.

A base film 201 formed from a metal material such as Ti (titanium), W(tungsten), Cr (chromium), Ta (tantalum), Ni (nickel), or Mo(molybdenum), an oxide thereof, a photocatalyst or the like ispreferably formed on the substrate 100 by a sputtering method, anevaporation method, or a droplet discharging method. The base film 201may be formed to have a film thickness of from 0.01 nm to 10 nm;however, a layer structure is not necessarily needed since it may beformed extremely thin. Note that this base film 201 is provided to formthe gate electrode with good adhesiveness. When adequate adhesiveness isobtained, the gate electrode may be directly formed on the substrate 100by a droplet discharging method without forming the base film 201.Alternatively, an atmospheric plasma treatment may be performed. Withoutlimiting to this step, in the case where a conductive layer is formedover an organic layer, an inorganic layer, a metal layer or the like bya droplet discharging method, or an organic layer, an inorganic layer, ametal layer or the like is formed over a conductive layer formed by adroplet discharging method, the same treatment may be performed so as tothe adhesiveness with the conductive layer.

A gate wiring 202, and gate electrodes 203 and 204 are formed on thebase film 201 by discharging a composition containing a conductivematerial by a droplet discharging method. The composition containingparticles of a metal such as Ag (silver), Au (gold), Cu (copper), W(tungsten), or Al (aluminum) as the main component can be used as theconductive material for forming these layers. Further, a compositionmainly containing Cu particles coated with Ag, or particles using Ni(nickel) or NiB (nickel boron) as the buffer layer may be employed.Specifically, the gate wiring is preferable to be low resistance.Therefore, a composition in which any one of gold, silver, or copperdissolved or dispersed in a solvent is preferably used, and morepreferably silver or copper with low resistance may be used inconsideration of a specific resistance value. Alternatively, alamination of silver and copper may be used. Silver that has beenapplied very thinly may be plated with copper to be a thicker wiring,since silver is so expensive. The surface of the applied silver is roughand easy to be plated. As the plating method, there are a method ofdipping a substrate into a plating solution, a method of flowing aplating solution over a substrate, and the like. When silver and copperare used, a barrier layer may be provided additionally as a measureagainst impurities. Nickel boron (NiB) may be used for the barrier layeras well as a silicon nitride film. The surface can be smoothed by nickelboron. A solvent corresponds to ester such as butyl acetate, alcoholssuch as. isopropyl alcohol, an organic solvent such as acetone, and thelike. Surface tension and viscosity are appropriately adjusted byadjusting density of a solvent and adding a surface activator or thelike.

A diameter of a nozzle used in a droplet discharging method is set to befrom 0.02 μm to 100 μm (preferably, 30 μm or less), and a dischargingamount of a composition discharged from the nozzle is preferably set tobe from 0.001 pl to 100 pl (more preferably, 10 pl or less). There aretwo types of an on-demand type and a continuous type for a dropletdischarging method, either of which may be used. Furthermore, there is apiezoelectric system using properties of transforming by applyingvoltage to a piezoelectric material and a heating system that boils acomposition by a heater provided in a nozzle and discharges thecomposition for a nozzle to be used in a droplet discharging method,either of which may be used. A distance between an object and adischarging outlet of a nozzle is preferable to be made as close aspossible to drop a droplet at a desired place, which is preferably setto be from 0.1 mm to 3 mm (more preferably, 1 mm or less). While keepingthe relative distance, either the nozzle or the object moves and thus, adesired pattern is drawn. A plasma treatment may be carried out on asurface of the object before discharging a composition. This is becausean advantage that a surface of the subject becomes hydrophilic andlyophobic when the plasma treatment is carried out, can be obtained. Forexample, it becomes hydrophilic to purified water and it becomeslyophobic to a paste dissolved with alcohol.

The step of discharging a composition may be performed under lowpressure. This is because a solvent of the composition is volatilizeduntil the composition is attached onto an object since it is discharged.Thus, steps of baking and drying later can be omitted or performed witha shorter time. After discharging the composition, either or both stepsof drying and baking is/are carried out by irradiation of laser light,rapid thermal annealing, heating furnace, or the like under atmosphericpressure or low pressure. Both the steps of drying and baking are stepsof heat treatment. For example, drying is carried out at 100° C. for 3minutes and baking is carried out at temperatures from 200° C. to 350°C. for 15 to 120 minutes. The steps of baking and drying have eachdifferent object, and need each different temperature and time. In orderto carry out the steps of drying and baking favorably, a substrate maybe heated, of which temperatures are set to be from 100° C. to 800° C.(preferably, temperatures from 200° C. to 350° C.), depending on amaterial of a substrate or the like. Through this step, a solvent in acomposition is volatilized or dispersant is removed chemically, and theresin in the periphery cures and shrinks, thereby accelerating fusionand welding. It is carried out under an oxygen atmosphere, a nitrogenatmosphere, or the air. However, this step is preferable to be carriedout under an oxygen atmosphere in which a solvent decomposing ordispersing a metal element is easily removed.

A continuous-wave or pulsed gas laser or solid state laser may be usedfor irradiation with laser light. There is an excimer laser or the likeas the gas laser, and there is a laser using a crystal such as YAG orYVO₄ doped with Cr, Nd, or the like as the solid state laser. It ispreferable to use a continuous-wave laser in terms of the laser lightabsorptance. In addition, a so-called hybrid method of laser irradiationcombining a continuous oscillation and a pulsed oscillation may be alsoused. However, a heat treatment by irradiation of laser light may becarried out rapidly for several microseconds to several tens of seconds,based on the heat resistance of a substrate. Rapid Thermal Annealing(RTA) is carried out by applying heat rapidly for several microsecondsto several minutes by rapidly raising temperature by using a halogenlamp, an infrared lamp that emits light from ultraviolet light toinfrared light, or the like under an atmosphere of an inert gas. Thistreatment is carried out rapidly; therefore, substantially, only a thinfilm of an uppermost surface can be heated, and thus, there is advantagethat the lower layer is not affected.

After forming the gate wiring 202, and the gate electrodes 203 and 204,it is desirable to carry out one of the following two steps for atreatment of the base film 201 which is exposed in the surface.

A first method is a step of forming an insulating layer 205 byinsulating the base film 201 not overlapping with the gate wiring 202,the gate electrodes 203 and 204 (FIG. 4B). In other words, the base film201 not overlapping with the gate wiring 202, the gate electrodes 203and 204 are oxidized and insulated. In the case of insulating the basefilm 201 by oxidizing in this manner, the base film 201 is preferablyformed to have a film thickness of from 0.01 nm to 10 nm, so that it canbe easily oxidized. Note that either a method of exposing to an oxygenatmosphere or a heat treatment may be used as the oxidizing method.

A second method is a step of etching and removing the base film 201,using the gate wiring 202, the gate electrodes 203 and 204 as a mask. Inthe case of using this step, there is no restriction on a film thicknessof the base film 201.

Next, a gate insulating layer 206 is formed with a single layerstructure or a laminated structure by using a plasma CVD method or asputtering method (FIG. 4C). As a specifically preferable mode, alamination body of three layers of an insulating layer 207 made fromsilicon nitride, an insulating layer 208 made from silicon oxide, and aninsulating layer 209 made from silicon nitride is formed as the gateinsulating layer. Note that a rare gas such as argon may be contained ina reactive gas and mixed into an insulating layer to be formed in orderto form a dense insulating layer with little gate leak current at a lowdeposition temperature. Deterioration by oxidation can be prevented byforming a first layer to be in contact with the gate wiring 202, thegate electrodes 203 and 204 from silicon nitride or silicon oxynitride.Nickel boron (NiB) is used for the first layer to be in contact with thegate wiring 202, and the gate electrodes 203 and 204. Thus, the surfacecan be smoothed.

Next, a semiconductor film 210 is formed. The semiconductor film 210 isformed from an AS or SAS manufactured with a vapor phase growth methodby using a semiconductor material gas typified by silane or germane or asputtering method. A plasma CVD method or a thermal CVD method can beused as the vapor phase growth method.

In the case of using a plasma CVD method, an AS is formed from SiH₄which is a semiconductor material gas or a mixed gas of SiH₄ and H₂.When SiH₄ is diluted with H₂ 3 times to 1000 times to make a mixed gasor when Si₂H₆ is diluted with GeF₄ so that a gas flow rate of Si₂H₆:GeF₄is from 20 to 40:0.9, an SAS of which Si composition ratio is 80% ormore can be obtained. Specifically, the latter case is preferable sincethe semiconductor film 210 can have crystallinity from an interface withthe base.

A mask 211 is formed at a position corresponding the gate electrodes 203and 204 by discharging selectively a composition over the semiconductorfilm 210. A resin material which is one selected from a group of anepoxy resin, an acrylic resin, a phenol resin, a novolac resin, amelamine resin and a urethane resin is used for the mask 211. Also themask 211 is formed by a droplet discharging method using an organicmaterial such as benzocyclobutene, parylene, flare, orlight-transmitting polyimide; a compound material made frompolymerization such as siloxane-based polymer; a composition materialcontaining water-soluble homopolymer and water-soluble copolymer; or thelike. Alternatively, a commercial resist material containing aphotosensitive agent may be used. For example, a typical positive typeresist that a novolac resin, naphthoquinone diazide compounds as aphotosensitive agent and the like are dissolved or dispersed with aknown solvent; and a negative type resist that a base resin,diphenylsilanediol, an asid generation agent and the like are dissolvedor dispersed with a known solvent may be used. In using any one ofmaterials, surface tension and viscosity are appropriately adjusted byadjusting a concentration of a solvent or adding a surface activator orthe like.

The gate insulating layer 206 and the semiconductor film 210 are etchedusing the mask 211 (FIG. 5A). Consequently, the semiconductor film isformed so that an edge thereof does not protrude from (is not beyond) anedge of the gate insulating layer. Alternatively it is can be said thatthe semiconductor film is formed so that an edge thereof is aligned toan edge of the gate insulating layer. In other words, the edges existstraight. Either plasma etching or wet etching may be applied for theetching step. Plasma etching is suitable for processing a large-sizedsubstrate. A etching gas which is at least one selected from the groupof CF₄, NF₃ and the like as a fluorine-based gas and Cl₂, BCl₃ and thelike as a chlorine-based gas is used, and any one of He, Ar and the likemay be added appropriately. In addition, when an etching step ofatmospheric pressure discharging is applied, a local discharging processis also possible. Then, the mask 211 is removed, and a protective layer212 is formed by a droplet discharging method over the semiconductorfilm 210. The protective layer 212 is an insulating layer, and can beformed from an inorganic insulating material such as silicon oxide,silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride,aluminum oxynitride,; acrylic acid, methacrylic acid, and a derivativethereof; a heat-resistance high-polymer (high-molecular weight) materialsuch as polyimide, aromatic polyamide, or polybenzimidazole; inorganicsiloxane including a Si—O—Si bond, among the compounds made fromsilicon, oxygen and hydrogen, formed by using a siloxane-based materialas a start material; or an organic siloxane insulating material in whichhydrogen on silicon is substituted by an organic group such as methyl orphenyl. When the protective layer is formed from a material such asphotosensitive acrylic or photosensitive polyimide, it is preferablesince the side face thereof has a shape in which a curvature radiuschanges continuously and a thin film in the upper layer is formedwithout break. Thus protective layer has functions of ensuring cleannessat the interface and preventing the semiconductor film 210 from beingcontaminated by an organic material, a metal, water vapor or the like.The protective layer also has a function as an interlayer film.

The protective layer 212 may be formed by the following method.Initially, an insulating layer such as silicon oxide, silicon nitride,or silicon oxynitride is formed by plasma CVD over the semiconductorfilm 210. Then, the protective layer 212 is formed by a dropletdischarging method and the protective layer 212 is used as a mask toperform an etching step. Thus, the insulating layer lies under theprotective layer 212, and a protective layer can be formed from alamination of the insulating layer and a siloxane based material or thelike.

Next, an n-type semiconductor film 213 is formed. The n-typesemiconductor film 213 may be formed by using a silane gas and aphosphine gas, and can be formed with AS or SAS. A composition includinga conductive material is discharged selectively to form a source anddrain wiring 214 by a droplet discharging method (FIG. 5A). As theconductive material for forming a wiring, a composition mainlycontaining a metal particle such as Ag (silver), Au (gold), Cu (copper),W (tungsten), or Al (aluminum) can be used. A lamination of silver andcopper or the like may be used. A light-transmitting indium tin oxide(ITO), ITSO including an indium tin oxide and silicon oxide, organicindium, organotin, zinc oxide, titanium nitride or the like may becombined.

The n-type semiconductor film 213 is etched by using the source anddrain wiring 214 as a mask to form n-type semiconductor films 215 and216 for forming a source and drain region (FIG. SB). Either plasmaetching or wet etching may be applied for the etching step. Plasmaetching is suitable for processing a large-sized substrate. A etchinggas which is at least one selected from the group of CF₄, NF₃ and thelike as a fluorine-based gas and Cl₂, BCl₃ and the like as achlorine-based gas is used, and any one of He, Ar and the like may beadded appropriately. In addition, when an etching step of atmosphericpressure discharging is applied, a local discharging process is alsopossible. Thereafter, a passivation layer 217 made of silicon nitride orsilicon oxynitride is formed over the entire surface.

An interlayer film 218 is formed by a droplet discharging method in awhole region except a portion connecting electrically with the sourceand drain wiring 214 (FIG. 6A). Alternatively, the interlayer film 218may be formed by a droplet discharging method in only a wiring portionexcept the portion connecting electrically with the source and drainwiring 214, as another method. This interlayer film is an insulatinglayer and can be formed from an inorganic insulating material such assilicon oxide, silicon nitride, silicon oxynitride, aluminum oxide,aluminum nitride, aluminum oxynitride, or the like; acrylic acid,methacrylic acid, and a derivative thereof; a heat-resistancehigh-polymer (high-molecular weight) material such as polyimide,aromatic polyamide, or polybenzimidazole; inorganic siloxane including aSi—O—Si bond, among the compounds made from silicon, oxygen andhydrogen, formed by using a siloxane-based material as a start material;or an organic siloxane insulating material in which hydrogen on siliconis substituted by an organic group such as methyl or phenyl. When theinterlayer film 228 is formed from a photosensitive material or anon-photosensitive material such as acrylic or polyimide, it ispreferable since the side face thereof has a shape in which a curvatureradius changes continuously and a thin film in the upper layer is formedwithout break.

Next, a through-hole 219 is formed in a portion of the passivation layer217 by an etching step using the interlayer film 218 as a mask, and thesource and drain wiring 214 disposed in the lower layer thereof ispartially exposed. Either plasma etching or wet etching may be appliedfor the etching step. Plasma etching is suitable for processing alarge-sized substrate. A etching gas which is at least one selected fromthe group of CF₄, NF₃ and the like as a fluorine-based gas and Cl₂, BCl₃and the like as a chlorine-based gas is used, and any one of He, Ar andthe like may be added appropriately. In addition, when an etching stepof atmospheric pressure discharging is applied, a local dischargingprocess is also possible; therefore, there is no necessity to form amask over an entire surface of a substrate.

Also, the interlayer film 218 is formed over a whole surface of thesubstrate by a spin-coating method or a dipping method, and then athrough-hole 219 is formed by an etching step or the like. As the methodfor forming the through-hole 219, the following step may be employed.Initially, the whole surface of the substrate is coated with a couplingagent including fluorine such as fluoroalkylsilane, a liquid repellentorganic material including fluorine such as CHF₃ or the like as a liquidrepellent treatment, before forming the interlayer film 218. Then, amask material is applied to a portion to form a through hole, and theliquid-repellent agent that is in a portion except in the portionprovided with the mask is removed by O₂ ashing or the like. The mask isremoved, and the interlayer film 218 is applied to the whole surface ofthe substrate by a spin-coating method, a dipping method or a dropletdischarging method. Since the interlayer film 218 is not formed over theliquid-repellent portion, a through-hole 219 is formed by the formedinterlayer film 218 as a mask. When the liquid-repellent agent isapplied selectively to only a portion for a through hole with a dropletdischarging apparatus, steps of forming the mask, removing theliquid-repellent agent and removing the mask are not required.

A first electrode 220 is formed to be electrically connected to thesource and drain wiring 214. The first electrode 220 is formed fromindium tin oxide (ITO), indium tin oxide containing silicon oxide(ITSO), zinc oxide (ZnO), or the like by a sputtering method. Morepreferably, indium tin oxide containing silicon oxide is used with asputtering method by using a target in which silicon oxide of 2 wt. % to10 wt. % is contained in ITO. Moreover, an oxide conductive materialcontaining silicon oxide and in which zinc oxide (ZnO) of 2 wt. % to 20wt. % is mixed with indium oxide (hereinafter, also referred to as“IZO”) may be used.

A mask 221 may be formed by discharging selectively a composition overthe first electrode 220. A resin material such as an epoxy resin, anacrylic resin, a phenol resin, a novolac resin, a melamine resin, or aurethane resin is used for the mask 221. Also the mask 221 is formedwith a droplet discharging method by using an organic material such asbenzocyclobutene, parylene, flare, or light-transmitting polyimide; acompound material made from polymerization such as siloxane-basedpolymer; a composition material containing water-soluble homopolymer andwater-soluble copolymer; or the like. And also, a commercial resistmaterial containing a photosensitive agent may be used. For example, atypical positive type resist that a novolac resin, naphthoquinonediazide compounds as a photosensitive agent and the like are dissolvedor dispersed with a known solvent; and a negative type resist that abase resin, diphenylsilanediol, an asid generation agent and the likeare dissolved or dispersed with a known solvent may be used. In usingany one of materials, surface tension and viscosity are appropriatelyadjusted by adjusting a concentration of a solvent or adding a surfaceactivator or the like.

The first electrode 220 is etched by using the mask 221, and then, themask 221 is removed (FIG. 6D). Either plasma etching or wet etching maybe applied for the etching step. Plasma etching is suitable forprocessing a large-sized substrate. A etching gas which is at least oneselected from the group of CF₄, NF₃ and the like as a fluorine-based gasand Cl₂, BCl₃ and the like as a chlorine-based gas is used, and any oneof He, Ar and the like may be added appropriately. In addition, when anetching step of atmospheric pressure discharging is applied, a localdischarging process is also possible.

The first electrode 220 may be formed by selectively discharging acomposition containing a conductive material to electrically connectwith the source and drain wiring 214 by a droplet discharging method.The first electrode 220 serves as a pixel electrode. In the case ofmanufacturing a transmission type EL display panel, a compositioncontaining indium tin oxide (ITO), indium tin oxide containing siliconoxide (ITSO), zinc oxide (ZnO), tin oxide (SnO₂), or the like may beused for the first electrode 220. Then, a predetermined pattern may beformed from such a composition and a pixel electrode may be formed bybaking. On the other hand, in the case of a structure in which generatedlight is emitted to the opposite side of the substrate 100, that is, areflective EL display panel, a composition including mainly a metalparticle such as Ag (silver), Au (gold), Cu (copper) W (tungsten), or Al(aluminum) can be used.

An insulating layer 222 is formed by a droplet discharging method tocover the edge of the etched first electrode. This insulating layer 222can be formed from an inorganic insulating material such as siliconoxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminumnitride, aluminum oxynitride; acrylic acid, methacrylic acid, and aderivative thereof; a heat-resistance high-polymer (high-molecularweight) material such as polyimide, aromatic polyamide, orpolybenzimidazole; inorganic siloxane including a Si—O—Si bond, amongthe compounds made from silicon, oxygen, and hydrogen, formed by using asiloxane-based material as a start material; or an organic siloxaneinsulating material in which hydrogen on silicon is substituted by anorganic group such as methyl or phenyl. When the insulating layer 222 isformed from a photosensitive material or a non-photosensitive materialsuch as acrylic or polyimide, it is preferable since the edge thereofhas a shape in which a curvature radius changes continuously and a thinfilm in the upper layer is formed without break. Further, as for theinsulating layer 222, the insulating layer can be formed entirely by aspin-coating method or a dipping method, and a pattern can be formed byan etching step.

Through the above-mentioned steps, a TFT substrate for an EL displaypanel in which a bottom gate type (also referred to as a reverse staggertype) TFT and the first electrode are connected over the substrate 100is completed.

Before forming an EL layer 223, a heat treatment at 200° C. at theatmospheric pressure is carried out to remove the moisture adsorbed inthe insulating layer 222 or on the surface thereof. In addition, a heattreatment is carried out at temperatures from 200° C. to 400° C.,preferably from 250° C. to 350° C. under low pressure. It is preferableto form the EL layer 223 by a vacuum evaporation method or a dropletdischarging method under the low pressure without exposing to the air.

In addition, surface treatment may be additionally carried out byexposing the surface of the first electrode 220 to oxygen plasma orirradiating it with ultraviolet light. A second electrode 224 is formedon the EL layer 223 to form a light-emitting element by a sputteringmethod or a droplet discharging method. This light-emitting element hasa structure in which it is connected to the driving TFT 10000.

Subsequently, a sealant is formed over the substrate and the EL layerover the substrate is sealed by using the sealing substrate. Thereafter,a flexible wiring board may be connected to the gate wiring. The sameapplies to a signal wiring.

As mentioned above, in this embodiment mode, steps can be omitted sincea light-exposure step using a photomask is not employed. In addition, anEL display panel can be easily manufactured even when using a glasssubstrate of the fifth generation or later, in which one side of 1000 mmor more, by forming various kinds of pattern directly on a substrate bya droplet discharging method.

Embodiment mode 2

A method for manufacturing a channel etch type TFT is explained inEmbodiment mode 2.

A base film 201 is formed on a substrate 100, and a gate wiring 202,gate electrodes 203 and 204 are formed over the base film 201 bydischarging a composition including a conductive material. After thegate wiring 202, the gate electrodes 203 and 204 are formed, the exposedbase film 201 in the surface is treated and insulated to form aninsulating layer 205 or removed by etching using the gate wiring 202,the gate electrodes 203 and 204 as a mask. Then, a gate insulating layer206 is formed by plasma CVD or sputtering to have a single layerstructure or a laminated layer structure. More preferably, a laminationof three layers, an insulating layer 207 of silicon nitride, aninsulating layer 208 of silicon oxide and an insulating layer 209 ofsilicon nitride serves as the gate insulating layer. Further, asemiconductor film 210 serving as an active layer is formed. A mask 211is formed by discharging selectively a composition in a portioncorresponding to the gate electrodes 203 and 204, and the gateinsulating layer 206 and the semiconductor film 210 are etched by usingthe mask 211 over the semiconductor film 210. After that, the mask 211is removed. The above-mentioned steps are similar to those of Embodimentmode 1.

An n-type semiconductor film 301 is formed over the semiconductor film210. Then, a source and drain wiring 302 is formed by discharging acomposition including a conductive material selectively by a dropletdischarging method over the semiconductor film 301. Next, the n-typesemiconductor film 301 is etched by the source and drain wiring 302 as amask to form an n-type semiconductor film forming a source and drainregion (FIG. 7). The etching step may employ plasma etching or wetetching, but plasma etching is more suitable for a large size substrate.A etching gas which is at least one selected from the group of CF₄, NF₃and the like as a fluorine-based gas and Cl₂, BCl₃ and the like as achlorine-based gas is used, and any one of He, Ar and the like may beadded appropriately. If etching step with atmospheric pressuredischarging is applied, local discharging process is also possible.

Subsequent steps are similar to those of Embodiment mode 1.

Embodiment mode 3

A method for manufacturing a channel protective type TFT in which afirst electrode is formed over a base film is explained in Embodimentmode 3.

FIG. 9A shows a step of forming a first electrode over a substrate 100,and FIG. 9B shows a step of forming a gate electrode, and a gate wiringconnected to the gate electrode by a droplet discharging method. Notethat FIG. 9A shows schematically a longitudinal sectional structure, andFIG. 13 shows a planar structure corresponding to a-b, c-d and e-fthereof, and thus, the figures can be referred to at the same time.

A plastic substrate having the heat resistance that can withstandprocessing temperature of the manufacturing step or the like can be usedfor the substrate 100, in addition to a non-alkaline glass substratesuch as barium borosilicate glass, alumino borosilicate glass, oraluminosilicate glass manufactured by a fusion method or a floatingmethod, and a ceramic substrate. In addition, a semiconductor substratesuch as single crystal silicon, a substrate in which a surface of ametal substrate such as stainless is provided with an insulating layermay be applied too.

A base film 401 formed from a metal material such as Ti (titanium), W(tungsten), Cr (chromium), Ta (tantalum), Ni (nickel), or Mo(molybdenum), an oxide thereof, a photocatalyst or the like ispreferably formed on the substrate 100 by a sputtering method, a vapordeposition method or a droplet discharging method. The base film 401 maybe formed to have a film thickness of 0.01 nm to 10 nm; however, a layerstructure is not necessarily needed since it may be formed extremelythin. Note that this base film 401 is provided to form the gateelectrode with good adhesiveness. When adequate adhesiveness isobtained, the electrode may be directly formed on the substrate 100 by adroplet discharging method without forming the base film 401.Alternatively, an atmospheric pressure plasma treatment may beconducted. Further, without limiting to this step, a similar treatmentmay be conducted so as to enhance adhesiveness with a conductive layer,in the case of forming the conductive layer over an organic layer, aninorganic layer or a metal layer by a droplet discharging method, orforming an organic layer, an inorganic layer or a metal layer over theconductive layer formed by a droplet discharging method, withoutlimiting to the step.

A first electrode 402 is formed over the base film 401. The firstelectrode 402 is formed from indium tin oxide (ITO), indium tin oxidecontaining silicon oxide (ITSO), zinc oxide (ZnO), or the like by asputtering method. More preferably, indium tin oxide containing siliconoxide is used with a sputtering method by using a target in whichsilicon oxide of 2 wt. % to 10 wt. % is contained in ITO. Moreover, anoxide conductive material which contains silicon oxide and in which zincoxide (ZnO) of 2 wt. % to 20 wt. % is mixed with indium oxide may beused.

A mask 403 is formed by discharging selectively a composition over thefirst electrode 402. A resin material which is one selected from a groupof an epoxy resin, an acrylic resin, a phenol resin, a novolac resin, amelamine resin and a urethane resin may be used for the mask 403. Alsothe mask may be formed by a droplet discharging method by using anorganic material such as benzocyclobutene, parylene, flare orlight-transmitting polyimide; a compound material made frompolymerization such as siloxane-based polymer; a composition materialcontaining water-soluble homopolymer and water-soluble copolymer; or thelike. Alternatively, a commercial resist material containing aphotosensitive agent may be used. For example, a typical positive typeresist that a novolac resin, naphthoquinone diazide compounds as aphotosensitive agent and the like are dissolved or dispersed with aknown solvent; and a negative type resist that a base resin,diphenylsilanediol, an asid generation agent and the like are dissolvedor dispersed with a known solvent may be used. In using any one ofmaterials, surface tension and viscosity are appropriately adjusted byadjusting a concentration of a solvent or adding a surface activator orthe like.

The first electrode 402 is etched by using the mask 403, and then, themask 403 is removed (FIG. 9A). Either plasma etching or wet etching maybe applied for the etching step. Plasma etching is suitable forprocessing a large-sized substrate. A etching gas which is at least oneselected from the group of CF₄, NF₃ and the like as a fluorine-based gasand Cl₂, BCl₃ and the like as a chlorine-based gas is used, and any oneof He, Ar and the like may be added appropriately. In addition, when anetching step of atmospheric pressure discharging is applied, a localdischarging process is also possible.

The first electrode 402 may be formed by selectively discharging acomposition containing a conductive material by a droplet dischargingmethod. In the case of manufacturing a transmission type EL displaypanel, a composition containing indium tin oxide (ITO), indium tin oxidecontaining silicon oxide (ITSO), zinc oxide (ZnO), tin oxide (SnO₂), orthe like may be used for the first electrode 402. Then, a predeterminedpattern may be formed by using such a composition and a pixel electrodemay be formed by baking. On the other hand, in the case of a structurein which generated light is emitted to the opposite side of thesubstrate 100, that is, a reflective EL display panel, a compositionincluding mainly a metal particle such as Ag (silver), Au (gold), Cu(copper) W (tungsten), or Al (aluminum) can be used.

Gate wirings 404 and 407, and gate electrodes 405 and 406 are formed bydischarging a composition containing a conductive material by a dropletdischarging method. The composition containing particles of a metal suchas Ag (silver), Au (gold), Cu (copper), W (tungsten), or Al (aluminum)as the main component can be used as the conductive material for formingthese layers. Specifically, the gate wiring is preferable to be lowresistance. Therefore, a solution in which any one of gold, silver, andcopper dissolved or dispersed in a solvent is preferably used, and morepreferably silver or copper with low resistance is used in considerationof a specific resistance value. Alternatively, a lamination of silverand copper may be used. Silver that has been applied very thinly may beplated with copper to be a thicker wiring, since silver is so expensive.The surface of the applied silver is rough and easy to be plated. As theplating method, there is a method of dipping in a plating solution orflowing a plating solution. When silver and copper are used, a barrierlayer may be provided additionally as a measure against impurities.Nickel boron (NiB) may be used for the barrier layer as well as asilicon nitride film. The surface can be smoothed by nickel boron. Asolvent corresponds to ester such as butyl acetate, alcohols such asisopropyl alcohol, an organic solvent such as acetone, or the like.Surface tension and viscosity are appropriately adjusted by adjusting aconcentration of a solvent and adding a surface activator.

A diameter of a nozzle used in a droplet discharging method is set to befrom 0.02 μm to 100 μm (preferably, 30 μm or less), and a dischargingamount of a composition discharged from the nozzle is preferably set tobe from 0.001 pl to 100 pl (more preferably, 10 pl or less). There aretwo types of an on-demand type and a continuous type for a dropletdischarging method, either of which may be used. Furthermore, there is apiezoelectric system using properties of transforming by applyingvoltage to a piezoelectric material and a heating system that boils acomposition by a heater provided in a nozzle and discharges thecomposition for a nozzle to be used in a droplet discharging method,either of which may be used. A distance between an object and adischarging outlet of a nozzle is preferable to be made as close aspossible to drop a droplet at a desired place, which is preferably setto be from 0.1 mm to 3 mm (more preferably, 1 mm or less). While keepingthe relative distance, either the nozzle or the object moves and thus, adesired pattern is drawn. A plasma treatment may be carried out on asurface of the object before discharging a composition. This is becausean advantage that a surface of the subject becomes hydrophilic andlyophobic when the plasma treatment is carried out, can be obtained. Forexample, it becomes hydrophilic to purified water and it becomeslyophobic to a paste dissolved with alcohol.

The step of discharging a composition may be performed under lowpressure. This is because a solvent of the composition is voltailizeduntil the composition is attached onto an object since it is discharged.Thus, steps of baking and drying later can be omitted or performed witha shorter time. After discharging the composition, either or both stepsof drying and baking is/are carried out by irradiation of laser light,rapid thermal annealing, heating furnace, or the like under atmosphericpressure or low pressure. Both the steps of drying and baking are stepsof heat treatment. For example, drying is carried out at 100° C. for 3minutes and baking is carried out at temperatures from 200° C. to 350°C. for 15 to 120 minutes. The steps of baking and drying have eachdifferent object, and need each different temperature, and time. Inorder to carry out the steps of drying and baking favorably, a substratemay be heated, of which temperatures are set to be from 100° C. to 800°C. (preferably, temperatures from 200° C. to 350° C.), depending on amaterial of a substrate or the like. Through this step, a solvent in acomposition is volatilized or dispersant is removed chemically, and theresin in the periphery cures and shrinks, thereby accelerating fusionand welding. It is carried out under an oxygen atmosphere, a nitrogenatmosphere, or the air. However, this step is preferable to be carriedout under an oxygen atmosphere in which a solvent decomposing ordispersing a metal element is easily removed.

A continuous-wave or pulsed gas laser or solid state laser may be usedfor irradiation with laser light. There is an excimer laser, or the likeas the gas laser, and there is a laser using a crystal such as YAG orYVO₄ doped with Cr, Nd, or the like as the solid state laser. It ispreferable to use a continuous-wave laser in terms of the laser lightabsorptance. In addition, a so-called hybrid method of laser irradiationcombining a continuous oscillation and a pulsed oscillation may be alsoused. However, a heat treatment by irradiation of laser light may becarried out rapidly for several microseconds to several tens of seconds,based on the heat resistance of a substrate. Rapid Thermal Annealing(RTA) is carried out by applying heat rapidly for several microsecondsto several minutes by rapidly raising temperature by using a halogenlamp, an infrared lamp that emits light from ultraviolet light toinfrared light, or the like under an atmosphere of an inert gas. Thistreatment is carried out rapidly; therefore, substantially, only a thinfilm of an uppermost surface can be heated, and thus, there is advantagethat the lower layer is not affected.

After forming the gate wirings 404 and 407, and the gate electrodes 405and 406, it is desirable to carry out one of the following two steps asa treatment of the base film 201 that is exposed in the surface.

A first method is a step of forming an insulating layer 408 byinsulating the base film 401 not overlapping with the first electrode402, the gate wirings 404 and 407 and the gate electrodes 405 and 406(FIG. 9B). In other words, the base film 401 not overlapping with thefirst electrode 402, the gate wirings 404 and 407 and the gateelectrodes 405 and 406 are oxidized and insulated. In the case ofinsulating the base film 401 by oxidizing in this manner, the base film401 is preferably formed to have a film thickness of from 0.01 nm to 10nm, so that it can be easily oxidized. Note that either a method ofexposing to an oxygen atmosphere or a heat treatment may be used as theoxidizing method.

A second method is a step of etching and removing the base film 401,using the first electrode 402, the gate wirings 404 and 407 and the gateelectrodes 405 and 406 as a mask. In the case of using this step, thereis no restriction on a film thickness of the base film 401.

Next, a gate insulating layer 409 is formed in a single layer structureor a laminated structure by using a plasma CVD method or a sputteringmethod (FIG. 9C). As a specifically preferable mode, a lamination bodyof three layers of an insulating layer 410 made from silicon nitride, aninsulating layer 411 made from silicon oxide, and an insulating layer412 made from silicon nitride is formed as the gate insulating layer.Note that a rare gas such as argon may be contained in a reactive gasand mixed into an insulating layer to be formed in order to form a denseinsulating layer with little gate leak current at a low depositiontemperature. Deterioration by oxidation can be prevented by forming afirst layer to be in contact with the gate wirings 404 and 407, and thegate electrodes 405 and 406 from silicon nitride or silicon oxynitride.Nickel boron (NiB) is used for the first layer to be in contact with thegate wirings 404 and 407, and the gate electrodes 405 and 406. Thus, thesurface can be smoothed.

Next, a semiconductor film 413 is formed. The semiconductor film 413 isformed from an AS or SAS manufactured with a vapor phase growth methodby using a semiconductor material gas typified by silane or germane or asputtering method. A plasma CVD method or a thermal CVD method can beused as the vapor phase growth method.

In the case of using a plasma CVD method, an AS is formed from SiH₄which is a semiconductor material gas or a mixed gas of SiH₄ and H₂.When SiH₄ is diluted with H₂ 3 times to 1000 times to make a mixed gasor when Si₂H₆ is diluted with GeF₄ so that a gas flow rate of Si₂H₆:GeF₄is from 20 to 40:0.9, an SAS of which Si composition ratio is 80% ormore can be obtained. Specifically, the latter case is preferable sincethe semiconductor film 413 can have crystallinity from an interface withthe base.

A mask 414 is formed at a position corresponding to the gate electrodes405 and 406 by discharging selectively a composition over thesemiconductor film 413. A resin material such as an epoxy resin, anacrylic resin, a phenol resin, a novolac resin, a melamine resin, or aurethane resin is used for the mask 414. In addition, the mask 414 isformed by a droplet discharging method by using an organic material suchas benzocyclobutene, parylene, flare, or light-transmitting polyimide; acompound material made from polymerization such as siloxane-basedpolymer; a composition material containing water-soluble homopolymer andwater-soluble copolymer; or the like. Alternatively, a commercial resistmaterial containing a photosensitive agent may be used. For example, atypical positive type resist that a novolac resin, naphthoquinonediazide compounds as a photosensitive agent and the like are dissolvedor dispersed with a known solvent; and a negative type resist that abase resin, diphenylsilanediol, an asid generation agent and the likeare dissolved or dispersed with a known solvent may be used. In usingany one of the materials, surface tension and viscosity areappropriately adjusted by adjusting a concentration of a solvent oradding a surface activator or the like.

The insulating layer 409 and the semiconductor film 413 are etched byusing the mask 414 (FIG. 9D). Either plasma etching or wet etching maybe applied for the etching step. Plasma etching is suitable forprocessing a large-sized substrate. A etching gas which is at least oneselected from the group of CF₄, NF₃ and the like as a fluorine-based gasand Cl₂, BCl₃ and the like as a chlorine-based gas is used, and any oneof He, Ar and the like may be added appropriately. In addition, when anetching step of atmospheric pressure discharging is applied, a localdischarging process is also possible. Then, the mask 414 is removed, anda protective layer 415 is formed by a droplet discharging method overthe semiconductor film 413. The protective layer has functions ofensuring cleanness at the interface and preventing the semiconductorfilm 413 from being contaminated by impurities such as an organicmaterial, a metal, and water vapor. The protective layer also has afunction as an interlayer film.

Next, an n-type semiconductor film 416 is formed. The n-typesemiconductor film 416 may be formed by using a silane gas and aphosphine gas, and can be formed with AS or SAS. A composition includingconductive material is discharged selectively to form a source and drainwiring 417 by a droplet discharging method (FIG. 10B). As the conductivematerial for forming the wiring, a composition mainly containing a metalparticle such as Ag (silver), Au (gold), Cu (copper), W (tungsten), orAl (aluminum) can be used. A lamination of silver and copper or the likemay be used. A light-transmitting indium tin oxide (ITO), ITSO includingan indium tin oxide and silicon oxide, organic indium, organotin, zincoxide, titanium nitride or the like may be combined.

The n-type semiconductor film 416 is etched by using the source anddrain wiring 417 as a mask to form n-type semiconductor films 418 and419 for forming a source and drain region (FIG. 10C). Thereafter, apassivation layer 420 made of silicon nitride or silicon oxynitride isformed over the entire surface.

An interlayer film 421 is formed by a droplet discharging method in awhole region except a light-emitting region (FIG. 11A). This interlayerfilm is an insulating layer and can be formed from an inorganicinsulating material such as silicon oxide, silicon nitride, siliconoxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride;acrylic acid, methacrylic acid, and a derivative thereof; aheat-resistance high-polymer (high-molecular weight) material such aspolyimide, aromatic polyamide, or polybenzimidazole; inorganic siloxaneincluding a Si—O—Si bond, among the compounds made from silicon, oxygenand hydrogen, formed by using a siloxane-based material as a startmaterial; or an organic siloxane insulating material in which hydrogenon silicon is substituted by an organic group such as methyl or phenyl.When the interlayer film is formed from a material such asphotosensitive acrylic or photosensitive polyimide, it is preferablesince the side face thereof has a shape in which a curvature radiuschanges continuously and a thin film in the upper layer is formedwithout break.

The passivation layer 420 in the light emitting region is etched by theinterlayer film 421 as a mask. Either plasma etching or wet etching maybe applied for the etching step. Plasma etching is suitable forprocessing a large-sized substrate. A etching gas which is at least oneselected from the group of CF₄, NF₃ and the like as a fluorine-based gasand Cl₂, BCl₃ and the like as a chlorine-based gas is used, and any oneof He, Ar and the like may be added appropriately. In addition, when anetching step of atmospheric pressure discharging is applied, a localdischarging process is also possible; therefore, there is no necessityto form a mask over an entire surface of a substrate.

Through the above-mentioned steps, a TFT substrate for an EL displaypanel in which a bottom gate type (also referred to as a reverse staggertype) TFT and the first electrode are connected over the substrate 100is completed.

Before forming an EL layer 422, a heat treatment at 200° C. in theatmospheric pressure is carried out to remove the moisture adsorbed inthe insulating layer 421 or on the surface thereof. In addition, a heattreatment is carried out at temperatures from 200° C. to 400° C.,preferably from 250° C. to 350° C. under low pressure. It is preferableto form the EL layer 422 by a vacuum evaporation method or a dropletdischarging method under the low pressure without exposing to the air.

In addition, a surface treatment may be additionally carried out byexposing the surface of the first electrode 402 to oxygen plasma orirradiating it with ultraviolet light. A second electrode 423 is formedon the EL layer 422 to form a light-emitting element by a sputteringmethod or a droplet discharging method. This light-emitting element hasa structure in which it is connected to the driving TFT 20000 (FIG.11B).

Subsequently, a sealant is formed over the substrate and the EL layerover the substrate is sealed by using a sealing substrate. Thereafter, aflexible wiring board may be connected to the gate wiring. The sameapplies to a signal wiring.

As mentioned above, in this embodiment mode, steps can be omitted sincea light-exposure step using a photomask is not employed. In addition, anEL display panel can be easily manufactured even when using a glasssubstrate of the fifth generation or later, in which one side of 1000 mmor more, by forming various kinds of pattern directly on a substrate bya droplet discharging method.

Embodiment mode 4

A method for manufacturing a channel etch type TFT in which a firstelectrode is formed over a base film is described in Embodiment mode 4.

A base film 401 is formed on a substrate 100, and a first electrode 402is formed on the base film 401. Then, a mask 403 is formed bydischarging a composition selectively over the first electrode 402. Thefirst electrode 402 is etched by using the mask 403, and then, the mask403 is removed. Next, gate wirings 404 and 407, and gate electrodes 405and 406 are formed by discharging a composition including a conductivematerial. After that, the exposed base film 401 in the surface istreated and insulated to form an insulating layer 408, or the base film401 is etched and removed by using the first electrode 402, the gatewirings 404 and 407, and the gate electrodes 405 and 406 as a mask.Then, a gate insulating layer 409 is formed by plasma CVD or sputteringto have a single layer structure or a laminated layer structure. Morepreferably, a lamination of three layers, an insulating layer 410 ofsilicon nitride, an insulating layer 411 of silicon oxide and aninsulating layer 412 of silicon nitride serves as the gate insulatinglayer. Further, a semiconductor film 413 serving as an active layer isformed. A mask 414 is formed by discharging selectively a composition ina portion corresponding to the gate electrodes 405 and 406 over thesemiconductor film 413, and the gate insulating layer 409 and thesemiconductor film 413 are etched by using the mask 414. After that, themask 414 is removed. The above-mentioned steps are similar to those ofEmbodiment mode 3.

An n-type semiconductor film 501 is formed over the semiconductor film413. Then, a source and drain wiring 502 is formed by discharging acomposition including a conductive material selectively by a dropletdischarging method over the semiconductor film 501. Next, the n-typesemiconductor film 501 is etched by the source and drain wiring 502 as amask to form an n-type semiconductor film forming a source and drainregion (FIG. 12).

Subsequent steps are similar to those of Embodiment mode 3.

Embodiment 1

In Embodiment modes 1 to 4, a capacitor can be also formed.

In the step of forming a gate wiring and a gate electrode, a capacitorelectrode layer is formed by discharging a composition including aconductive material by a droplet discharging method.

On the capacitor electrode layer, a gate insulating layer and asemiconductor film are formed. Next, a mask is formed on thesemiconductor film. The gate insulating layer and the semiconductor filmare etched by using the mask, and then, the mask is removed. A capacitorcan be formed by forming a wiring in a portion overlapping with thecapacitor electrode layer. In other cases, it is possible that acapacitor is formed by leaving the gate insulating layer selectively ina portion to be provided with the capacitor.

Embodiment 2

In an EL display device manufactured according to any one of Embodimentmodes 1 to 4, and Embodiment 1, a scanning line driver circuit can beformed on a substrate 100 by forming a semiconductor film with an SAS,as shown in FIG. 3.

FIG. 22 shows a block diagram of the scanning line driver circuit whichcomprises an n-channel TFT using the SAS that can obtain an electronfield-effect mobility of 1 to 15 cm²/V-sec.

A block denoted by 530 in FIG. 22 corresponds to a pulse output circuitfor outputting a sampling pulse for one stage and a shift registercomprises n pulse output circuits. Reference numeral 531 denotes abuffer circuit and a pixel 532 (which corresponds to the pixel 102 inFIG. 3) is connected thereto.

FIG. 23 shows a concrete configuration of the pulse output circuit 530which comprises n-channel TFTs 601 to 613. At the time, in considerationof an operating characteristic of the n-channel TFT using SAS, a size ofthe TFT may be determined. For example, when the channel length is set 8μm, the channel width may be set in the range of 10 to 80 μm.

FIG. 24 shows a concrete configuration of a buffer circuit 531 whichalso comprises n-channel TFT 620 to 635, similarly. At the time, inconsideration of an operating characteristic of the n-channel TFT usingSAS, a size of the TFT may be determined. For example, when the channellength is set 10 μm, the channel width may be set in the range of 10 to1800 μm.

It is necessary to connect respective TFTs by wirings to realize such acircuit. A configuration example of the wiring in that case is shown inFIG. 14. FIG. 14 shows a mode in which a gate electrode 204, a gateinsulating layer 206 (a lamination of three layers of an insulatinglayer 207 of silicon nitride, an insulating layer 208 of silicon oxide,and an insulating layer 209 of silicon nitride), a semiconductor film210 made of SAS, an insulating layer 212 forming a channel protectivelayer, n-type semiconductor films 215 and 216 forming a source anddrain, and a source and drain wiring 214 are formed, as in Embodimentmode 1. In this case, connection wirings 250, 251, and 252 are formedover the substrate 100 in the same step of forming the gate electrode204. A portion of the gate insulating layer is etched to expose theconnection wirings 250, 251, and 252, and TFTs are connectedappropriately by the source and drain wiring 214 and a connection wiring253 that is formed in the same step of forming the source and drainwiring 214, thereby realizing various circuits.

Embodiment 3

A mode of a light-emitting element that is applicable to Embodimentmodes 1 to 4 and Embodiments 1 and 2 is explained with reference toFIGS. 17A and 17B and FIGS. 18A and 18B.

FIG. 17A is an example in which a first electrode 11 is formed from alight-transmitting oxide conductive material. The light-transmittingoxide conductive material is preferable to be indium tin oxidecontaining silicon oxide of 1 atomic % to 15 atomic % in concentration.An EL layer 16 in which a hole injection layer or hole transportinglayer 41, a light-emitting layer 42, and an electron transporting layeror electron injecting layer 43 are laminated is provided over the firstelectrode 11. A second electrode 17 is formed of a first electrode layer33 comprising an alkaline metal or an alkaline earth metal, for example,LiF or MgAg and a second electrode layer 34 formed from a metal materialsuch as aluminum. The pixel having such a structure can radiate lightfrom the first electrode 11 side as shown by the arrow in the FIG. 17A.

FIG. 17B shows an example of radiating light from the second electrode17. A first electrode 11 is formed of a first electrode layer 35comprising a metal such as aluminum or titanium or a metal materialcomprising the metal and nitrogen of stoichiometric composition ratio orless in its concentration and a second electrode layer 32 comprising aconductive oxide material containing 1 atomic % to 15 atomic % ofsilicon oxide in its concentration. An EL layer 16 in which a holeinjecting layer or hole transporting layer 41, a light-emitting layer 42and an electron transporting layer or electron injecting layer 43 arelaminated is provided over the first electrode 11. A second electrode 17is formed of a third electrode layer 33 comprising an alkaline metal oran alkaline earth metal, for example, LiF or CaF and a fourth electrodelayer 34 comprising a metal material such as aluminum. However, eachthickness of the layers is set to 100 nm or less to obtain a state inwhich light can be transmitted. Accordingly, it is possible to radiatelight from the second electrode 17.

FIG. 18A shows an example of radiating light from a first electrode 11and shows a structure in which an electron transporting layer orelectron injecting layer 43, a light-emitting layer 42, and a holeinjecting layer or hole transporting layer 41 are sequentially laminatedas an EL layer. From the EL layer 16 side, a second electrode 17 isformed of a second electrode layer 32 comprising an oxide conductivematerial containing silicon oxide of 1 atomic % to 15 atomic % in itsconcentration, and a first electrode layer 31 comprising a metal such asaluminum or titanium, or a metal material containing the metal andnitrogen of stoichiometric composition ratio or less in itsconcentration. The first electrode 11 is formed from a third electrodelayer 33 comprising an alkaline metal or an alkaline earth metal, forexample, LiF or CaF and a fourth electrode layer 34 comprising a metalmaterial such as aluminum. However, each thickness of the layers is setto 100 nm or less to obtain a state in which light can be transmitted.Accordingly, it is possible to radiate light from the first electrode11.

FIG. 18B shows an example of radiating light from a second electrode 17and shows a structure in which an electron transporting layer orelectron injecting layer 43, a light-emitting layer 42, and a holeinjecting layer or hole transporting layer 41 are sequentially laminatedas an EL layer. A first electrode 11 has the same structure as that ofFIG. 15A and is formed to have a film thickness enough thick to reflectlight generated in the EL layer. The second electrode 17 is formed froma conductive oxide material comprising silicon oxide of 1 atomic % to 15atomic % in concentration. In this structure, the hole injecting layer41 is formed from a metallic oxide which is an inorganic material(typically, molybdenum oxide or vanadium oxide). Accordingly, oxygenintroduced in forming the second electrode 32 is supplied and thus, holeinjection properties are improved; therefore, a driving voltage can bedecreased.

The first electrode is formed from a light-transmitting oxide conductivematerial and the second electrode can transmit light or is formed from alight-transmitting oxide conductive material. At the time, light can beemitted (radiated) from opposite sides, in other words, from the firstand second electrode sides.

Embodiment 4

Next, a mode of mounting a driver circuit for driving on an EL displaypanel manufactured according to any one of Embodiment modes 1 to 4, andEmbodiment 1 is explained with reference to FIGS. 19A and 19B and FIGS.20A and 20B.

First, a display device to which a COG method is applied is explainedwith reference to FIGS. 19A and 19B. A pixel portion 1002 displayinginformation of a character, an image or the like and scanning linedriver circuits 1003 and 1004 are provided on a substrate 1001.Substrates 1005 and 1008 where plural driver circuits are provided aresectioned to be rectangular, and the sectioned driver circuits (referredto as a driver IC, hereinafter) are mounted on the substrate 1001. FIG.19A shows plural driver ICs 1007 and a mode of mounting a tape 1006 toan end of each driver ICs 1007. FIG. 19B shows a driver 1010 and a modeof mounting a tape 1009 to an end of each driver ICs 1010.

Next, a display device employing a TAB method is explained withreference to FIGS. 20A and 20B. A pixel portion 1002 and scanning linedriver circuits 1003 and 1004 are provided on a substrate 1001. FIG. 20Ashows a mode in which a plurality of tapes 1006 is attached onto thesubstrate 1001 and then, driver ICs 1007 are mounted on the tapes 1006.FIG. 20B shows a mode in which a tape 1009 is attached on the substrate1001 and then, a driver IC 1010 is mounted on the tape 1009. In the caseof applying the latter, metal pieces or the like that fixes the driverIC 1010 may be attached together in respect of the intensity.

A plurality of the driver ICs mounted on the EL display panel arepreferably on rectangular substrates 1005 and 1008 having one side of300 mm to 1000 mm or more in terms of enhancing the productivity.

A plurality of circuit patterns in which a driver circuit portion and aninput/output terminal are used as one unit may be formed on thesubstrates 1005 and 1008, and be divided and taken out finally. As forthe length of a long side of the driver IC, a rectangle with a long sideof 15 mm to 80 mm and a short side of 1 mm to 6 mm may be formed inconsideration of a length of one side of a pixel portion or a pixelpitch, as shown in FIGS. 19A and 20A. One side of the pixel portion1002, or a length of one side of the pixel portion 1002 plus one side ofeach driver circuit 1003 and 1004 may be employed to form the driver IC,as shown in FIGS. 19B and 20B.

The primacy of the driver IC over an IC chip is the length of the longerside. When a driver IC having a longer side of 15 to 80 mm is used, thenumber of driver ICs that are necessary for mounting corresponding tothe pixel region 1002 is smaller than that of IC chips. Therefore,process yield in manufacturing can be enhanced. When a driver IC isformed on a glass substrate, productivity is not detracted since thedriver IC is not limited to a shape of a substrate used as a motherbody. This is a great advantage, as compared with the case of taking outIC chips from a circular silicon wafer.

In FIGS. 19A, 19B, 20A and 20B, the driver IC 1007 or 1010 provided witha driver circuit is mounted on a region outside of the pixel region1002. The driver ICs 1007 and 1010 are signal line driver circuits. Inorder to form a pixel region corresponding to a RGB full color, 3072signal lines in a XGA class and 4800 signal lines in a UXGA class arenecessary. The described above number of signal lines form a leading outline by dividing into several blocks in an edge of the pixel region 1002and are gathered in accordance with a pitch of an output terminal of thedriver ICs 1007 and 1010.

The driver IC is preferably formed from a crystalline semiconductorformed over a substrate. The crystalline semiconductor is preferableformed by being irradiated with light of a continuous-wave laser.Therefore, a continuous-wave solid state laser or gas laser is used asthe oscillator for emitting the laser light. There is few crystaldefects when a continuous-wave laser is used. As a result, a transistorcan be manufactured by using a polycrystalline semiconductor film with alarge grain size. In addition, high-speed driving is possible sincemobility or a response speed is favorable, and it is possible to furtherimprove an operating frequency of an element than that of theconventional element; therefore, high reliability can be obtained sincethere is few properties variations. Note that a channel-length directionof a transistor may be same as a scanning direction of laser light tofurther improve an operating frequency. This is because the highestmobility can be obtained when a channel length direction of a transistorand a scanning direction of laser light with respect to a substrate arealmost parallel (preferably, from −30° to 30°) in a step of lasercrystallization by a continuous-wave laser. A channel length directionis same as a flowing direction of current in a channel formation region,in other words, a direction in which an electric charge moves. Thethusly formed transistor has an active layer including a polycrystallinesemiconductor film in which a crystal grain is extended in a channeldirection, and this means that a crystal grain boundary is formed almostalong a channel direction.

In carrying out laser crystallization, it is preferable to narrow downthe laser light largely, and a beam spot thereof preferably has a widthof approximately from 1 mm to 3 mm which is the same as that of ashorter side of the driver IC. In addition, in order to ensure anadequate and effective energy density for an object to be irradiated, anirradiated region of the laser light is preferably a linear shape.However, a linear shape here does not refer to a line in a proper sense,but refers to a rectangle or an oblong with a large aspect ratio. Forexample, the linear shape refers to a rectangle or an oblong with anaspect ratio of 2 or more (preferably from 10 to 10000). Accordingly,productivity can be improved by making a width of a beam spot of thelaser light and that of a shorter side of the driver IC even.

In FIGS. 19A and 19B and FIGS. 20A and 20B, a mode in which the scanningline driver circuit is integrally formed with the pixel portion and thedriver IC is mounted as a signal line driver circuit is shown. However,the present invention is not limited to this mode, and the driver IC maybe mounted as both a scanning line driver circuit and a signal linedriver circuit. In that case, it is preferable to make specifications ofthe driver ICs to be used on the scanning line side and the signal lineside different.

In the pixel region 1002, the signal line and the scanning line areintersected to form a matrix and a transistor is arranged in everyintersection portion. A TFT having a channel portion formed from anamorphous semiconductor or a semi-amorphous semiconductor can be used asthe transistor arranged in the pixel portion 1002, according to oneaspect of the invention. An amorphous semiconductor is formed by aplasma CVD method, a sputtering method or the like. It is possible toform a semi-amorphous semiconductor at a temperature of 300° C. or lesswith plasma CVD. There is a feature that a film thickness necessary toform a transistor is formed in a short time even in the case of anon-alkaline glass substrate of an external size of, for example, 550mm×650 mm. The feature of such a manufacturing technique is effective inmanufacturing a display device of a large-sized screen. In addition, asemi-amorphous TFT can obtain an electron field-effect mobility of 2 to10 cm²V/sec by forming a channel portion from an SAS. The TFT can beused as a switching element of a pixel or an element forming a scanningline driver circuit. Therefore, an EL display panel realizing asystem-on-panel can be manufactured.

In FIGS. 19A, 19B, 20A and 20B, it is supposed that a scanning linedriver circuit can be formed integrally on a substrate by using a TFTformed from a SAS as a semiconductor film according to Embodiment mode3. A scanning line driver circuit and a signal line driver circuit maybe both mounted as a driver IC in the case of using a TFT formed from anAS as a semiconductor film.

In that case, it is preferable that specifications of the driver ICsused on the scanning line side and the signal line side are different.For example, although a withstand voltage of about 30V for a transistormaking up the driver IC on the scanning line side is required, drivingfrequency is 100 kHz or less and comparatively high-speed response isnot required. Therefore, a channel length (L) of the transistor makingup the driver IC on the scanning line side is preferably set large. Onthe contrary, although the transistor of the driver IC on the signalline side has a withstand voltage of about 12 V, driving frequency isabout 65 MHz with 3 V and high-speed response is required. Accordingly,the channel length or the like of the transistor making up the driver ispreferably set with a micron rule.

As mentioned above, the driver circuit can be incorporated in the ELdisplay panel.

Embodiment 5

A structure of a pixel of an EL display panel as shown in thisembodiment is explained with reference to equivalent circuit diagramsshown in FIGS. 21A to 21F.

In a pixel shown in FIG. 21A, a signal line 810 and power supply lines811 to 813 are arranged in a column direction and a scanning line 814 isarranged in a row direction. In addition, a switching TFT 801, a drivingTFT 803, a current control TFT 804, a capacitor element 802, and alight-emitting element 805 are included therein. The capacitor element802 can be formed in another position depending on a structure, and thecapacitor element 802 is not necessarily provided.

A pixel shown in FIG. 21C has the same structure as the pixel shown inFIG. 21A except that gate electrodes of the TFTs 10000 and 20000 areconnected to a power supply line 813 arranged in a row direction. Thepixels shown in FIG. 21A and FIG. 21C are almost the same equivalentcircuit diagrams. However, the power supply lines are each formed fromconductive layers in different layers in the cases where the powersupply line 813 is arranged in a column direction (FIG. 21A) and thepower supply line 813 is arranged in a row direction (FIG. 21C). Here,wirings connected to the gate electrodes of the TFTs 10000 and 20000 arefocused and the figures are separately shown in FIG. 21A and 21C so asto show that the wirings are formed from different layers.

In the pixels shown in FIG. 21A and FIG. 21C, TFTs 803 and 804 areconnected in series. A channel length L₃ and a channel width W₃ of theTFT 803 and a channel length L₄ and a channel width W₄ of the TFT 804are set so as to satisfy L3/W3: L4/W4 =5 to 6000:1. As an example of thecase satisfying 6000:1, it is a case where L₃ is 500 μm, W₃ is 3 μm, L₄is 3 μm, and W₄ is 100 μm.

The TFT 803 operates in a saturation region and controls a current valueflowing through a light-emitting element 805. The TFT 804 operates in alinear region and controls supply of current to a light-emitting device805. It is preferable for the manufacturing step that these TFTs havethe same conductive type. In addition, not only an enhancement type butalso a depletion type TFT may be used for the TFT 803. In the presentinvention having the above-mentioned structure, the TFT 804 operates ina linear region; therefore, a slight variation of V_(GS) in the TFT 804does not affect a current value of the light-emitting element 805. Inother words, the current value of the light-emitting element 805 isdetermined depending on the TFT 803 that operates in a saturationregion. In the present invention having the above-mentioned structure, adisplay device in which image quality is improved by improving luminancevariation resulted from variations in TFT properties can be provided.

In the pixels shown in FIGS. 21A to 21C, the TFT 801 is a TFT forcontrolling input of a video signal to the pixel. When the TFT 801 turnsON and the video signal is inputted into the pixel, the video signal isstored in the capacitor element 802. FIGS. 21A and 21C each show astructure in which the capacitor element 802 is provided; however, thepresent invention is not limited thereto. When a gate capacitor or thelike can be used as the capacitor that can hold a video signal, thecapacitor element 802 may not be provided explicitly.

The light-emitting elements 805 and 844 have a structure in which anelectroluminescent layer is sandwiched between two electrodes, andpotential difference between a pixel electrode and an opposite electrode(between an anode and a cathode) are provided so that a forward biasvoltage is applied. The electroluminescent layer is formed from a widevariety of materials such as an organic material and an inorganicmaterial. Luminescence (fluorescence) in returning from a singletexcited state to a ground state and luminescence (phosphorescence) inreturning from a triplet excited state to a ground state are included inluminescence of this electroluminescent layer.

The pixel shown in FIG. 21B has the same structure as the pixel shown inFIG. 21A except that a TFT 806 and a scanning line 815 are added. In thesame manner, a pixel shown in FIG. 21D is the same as the pixelstructure shown in FIG. 21C except that a TFT 806 and a scanning line815 are added.

In the TFT 806, ON or OFF is controlled by the scanning line 816 that isnewly arranged. When the TFT 806 is turned ON, an electric charge heldin the capacitor element 802 is discharged, and the TFT 806 is turnedOFF. In other words, it is possible to make a state in which current isnot forced to flow into the light-emitting element 805 by disposing theTFT 806. Accordingly, in the structures of FIGS. 21B and 21D, alightning time can be started at the same time as or right after thebeginning of a writing time, without waiting for writing signals to allpixels, thereby enhancing a duty ratio.

In a pixel shown in FIG. 21E, a signal line 850 and power supply lines851 and 852 are arranged in a column direction, and a scanning line 853is arranged in a row direction. In addition, a switching TFT 841, adriving TFT 843, a capacitor element 842, and a light-emitting element844 are included therein. A pixel shown in FIG. 21F has the samestructure as the pixel shown in FIG. 21E except that a TFT 845 and ascanning line 854 are added. A duty ratio can be increased by disposingthe TFT 845 also in the structure of FIG. 21F. As described above, adriver circuit can be incorporated in an EL display panel.

Embodiment 6

One mode in which a protection diode is provided for each of a scanningline input terminal portion and a signal line input terminal portion isexplained with reference to FIG. 15. TFTs 541 and 542 are provided in apixel 102 in FIG. 15. The TFTs have the same structure as those inEmbodiment mode 1.

Protection diodes 561 and 562 are provided for the signal line inputterminal portion. These protection diodes are manufactured in the samestep as the TFT 541 or 542. The protection diodes 561 and 562 areoperated as a diode by connecting a gate of one protection diode to oneof a drain and a source of another protection diode. FIG. 16 shows anequivalent circuit diagram of the top view shown in FIG. 15.

The protection diode 561 comprises a gate electrode 550, a semiconductorfilm 551, a channel protective insulating layer 552, and a wiring 553.The protection diode 562 has the same structure. Common potential lines554 and 555 connecting to these protection diodes are formed in the samelayer as that of the gate electrode. Therefore, it is necessary to forma contact hole in a gate insulating layer so as to electrically connectto the wiring 553.

A mask may be formed by a droplet discharging method and an etching stepmay be carried out to form a contact hole in the gate insulating layer.In this case, when an etching step by atmospheric pressure dischargingis applied, a local discharging process is also possible, and it doesnot need to form a mask over an entire surface of a substrate.

A signal wiring 237 is formed in the same layer as that of a source anddrain wiring 214 in the TFT 541 and has a structure in which the signalwiring 237 connected thereto is connected to a source side or a drainside.

Protection diodes 563 and 564 of the input terminal portion of thescanning signal line side are also formed to have the same structure.According to one aspect the invention, the protection diodes provided inan input stage can be formed at the same time. Note that the position ofarranging the protection diode is not limited to this embodiment, butcan be also provided between a driver circuit and a pixel as shown inFIG. 3.

Embodiment 7

FIGS. 26 and 27 each show an embodiment of constituting an EL displaymodule by using a TFT substrate 200 manufactured by a dropletdischarging method. In FIGS. 26 and 27, a pixel portion 101 comprisingpixels 102 a to 102 c is formed on the TFT substrate 200.

In FIG. 26, the same TFT as that formed in a pixel or a protectivecircuit portion 701 operating in the same manner as a diode by beingconnected to a gate and one of a source or a drain of the TFT isprovided between a driver circuit 703 and the pixels 102 a to 102 c andoutside the pixel portion 101. A driver IC formed from a single crystalsemiconductor, a stick driver IC formed from a polycrystallinesemiconductor film over a glass substrate, a driver circuit formed froman SAS, or the like is applied to the driver circuit 703.

The TFT substrate 200 is fixed to a sealing substrate 236 by a spacer708 formed on the insulating layer by a droplet discharging method. Evenwhen the substrate has thin thickness or an area of the pixel portion isenlarged, the spacer is preferably provided to keep a gap between thetwo substrates constant. A light-transmitting resin material may befilled to solidify or anhydrous nitrogen or an inert gas may be filledin the gap over a light-emitting device 234 and between the TFTsubstrate 200 and the sealing substrate 236.

FIG. 26 shows the case where the light-emitting element 234 has a topemission type structure, in which light is radiated in a direction shownby the arrow thereof. Each pixel can carry out multicolor display bydifferentiating light-emitting colors by using the pixel 102 a for red,the pixel 102 b for green, and the pixel 102 c for blue. At this time,color purity of the luminescence emitted outside can be improved byforming a colored layer corresponding to each color on the side of thesealing substrate 236. In addition, the pixels 102 a, 102 b, and 102 cmay be each used as the white light-emitting element, and combined withthe colored layers.

An external circuit 705 is connected to a scanning line or signal lineconnection terminal provided on one end of the TFT substrate 200 with awiring board 704. In addition, a heat pipe 706 and a heat sink 707 maybe provided to be in contact with the TFT substrate 200 or in vicinitythereof to have a structure in which a heat dissipation effect isimproved.

FIG. 26 shows a top emission type EL module; however, a bottom emissionstructure may be employed by changing the structure of thelight-emitting element or the arrangement of the external circuitsubstrate.

FIG. 27 shows an example in which a resin film 710 is attached by usinga sealant 235 and an adhesive resin 702 onto the side where a pixelportion is formed over a TFT substrate 200 to form a sealing structure.A gas barrier film preventing penetration of water vapor may be providedon the surface of the resin film 710. FIG. 27 shows a bottom emissionstructure in which light of a light-emitting element is emitted throughthe substrate; however, a top emission structure is also acceptable bygiving light-transmitting properties to the resin film 710 or theadhesive resin 702. In either case, much more thin and lighter displaydevice can be obtained by adopting a film sealing structure.

Embodiment 8

An EL television receiver can be completed by an EL display modulemanufactured according to Embodiment mode 1. FIG. 28 shows a blockdiagram of a main structure of the EL television receiver. There are acase where a pixel portion 101 is formed alone in an EL display panel901 and a scanning line driver circuit 903 and a signal line drivercircuit 902 are mounted by a TAB method as the structure shown in FIG.1; and a case where the pixel portion 101 is formed in the EL displaypanel 901 and the scanning line driver circuit 903 and the signal linedriver circuit 902 are mounted in the periphery thereof by a COG methodas the structure shown in FIG. 2; a case where a TFT is formed from anSAS, and the pixel portion 101 and the scanning line driver circuit 903are formed integrally on a substrate, and the signal line driver circuit902 is separately mounted as a driver IC as the structure shown in FIG.3; and the like. However, any one mode of the cases may be applied.

As another structure of an external circuit, an input side of a videosignal includes a video signal amplifier circuit 905 that amplifies avideo signal among signals received by a tuner 904; a video signalprocessing circuit 906 that converts a signal outputted from the videosignal amplifier circuit 905 into a color signal corresponding to eachcolor of red, green, and blue; a control circuit 907 for converting thevideo signal into an input specification of a driver IC; and the like.The control circuit 907 outputs a signal into the scanning line side andthe signal line side, respectively. In the case of digital driving, asignal division circuit 908 may be provided on the signal line side andmay have a structure in which input digital signals are divided into msignals and supplied.

An audio signal, among signals received from the tuner 904, istransmitted to an audio signal amplifier circuit 909, and an outputsignal from the audio signal amplifier circuit 909 is supplied to aspeaker 913 through an audio signal processing circuit 910. A controlcircuit 911 receives control information of a receiving station (areceiving frequency) or sound volume from an input portion 912 andtransmits a signal to the tuner 904 or the audio signal processingcircuit 910.

As shown in FIG. 29, a television receiver can be completed byincorporating the EL module illustrated in FIGS. 26 and 27 into a casing920 by incorporating such an external circuit. A display screen 921 isformed by the EL display module, and a speaker 922, operation switches924, and the like are provided as other attached equipment. Accordingly,the television receiver can be completed according to the presentinvention.

Of course, the present invention is not limited to the televisionreceiver and is applicable to various use, in particular, as a displaymedium with a large-sized area such as an information display board at astation, an airport, etc., or an advertisement display board etc., onthe street as well as a monitor of a personal computer. The presentinvention is not limited to a large-size substrate, and is applicable toa comparatively small display medium such as a cellular phone.

1. A method of manufacturing a light-emitting device comprising the steps of: forming a gate electrode by a droplet discharging method over a substrate; forming a gate insulating layer and a first semiconductor film over the gate electrode; forming a first mask by a droplet discharging method over the first semiconductor film; etching the semiconductor film and the gate insulating layer continuously with the first mask to form a patterned gate insulating film and a patterned first semiconductor film; removing the first mask; forming a protective layer over the patterned first semiconductor film after removing the first mask; forming a second semiconductor film including one conductivity type impurity over the patterned first semiconductor film and the protective layer; forming a source wiring and a drain wiring by a droplet discharging method over the second semiconductor film; and etching the second semiconductor film over the protective layer by the source wiring and the drain wiring as a second mask.
 2. A method of manufacturing a light-emitting device comprising the steps of: forming a gate electrode of a switching thin film transistor and a gate electrode of a driving thin film transistor by a droplet discharging method over a substrate; forming a gate insulating layer and a first semiconductor film over the gate electrode of the switching thin film transistor and the gate electrode of the driving thin film transistor; forming a first mask by a droplet discharging method over the first semiconductor film; etching the first semiconductor film and the gate insulating layer continuously with the first mask to form a patterned gate insulating film and a patterned first semiconductor film and to expose a portion of the gate electrode of the driving thin film transistor; removing the first mask; forming a protective layer over the patterned first semiconductor film after removing the first mask; forming a second semiconductor film including one conductivity type impurity; forming a source wiring and a drain wiring by a droplet discharging method, at the same time, and connecting at least one of the source wiring and the drain wiring to the gate electrode of the driving thin film transistor; and etching the second semiconductor film over the protective layer by the source wiring and the drain wiring as a second mask.
 3. The method of manufacturing a light-emitting device according to claim 1 or 2, wherein the step of forming the gate insulating film and the first semiconductor film over the gate electrode is performed continuously without being exposed to an air.
 4. A method of manufacturing a light-emitting device comprising the steps of: forming a gate electrode by a droplet discharging method over a substrate having an insulating surface or a substrate having a base surface that is exposed to a pretreatment; forming a base film over the gate electrode as a pretreatment; forming a gate insulating layer and a first semiconductor film over the base film forming a first mask by a droplet discharging method over the first semiconductor film; etching the first semiconductor film and the gate insulating layer continuously with the first mask to form a patterned gate insulating film and a patterned first semiconductor film; removing the first mask; forming a protective layer over the patterned first semiconductor film after removing the first mask; forming a second semiconductor film including one conductivity type impurity; forming a source wiring and a drain wiring by a droplet discharging method; and etching the second semiconductor film over the protective layer by the source wiring and the drain wiring as a second mask.
 5. A method of manufacturing a light-emitting device comprising the steps of: forming a gate electrode of a switching thin film transistor and a gate electrode of a driving thin film transistor by a droplet discharging method over a substrate; forming a base film over the gate electrode of the switching thin film transistor and the gate electrode of the driving thin film transistor as a pretreatment; forming a gate insulating layer and a first semiconductor film over the base film; forming a first mask by a droplet discharging method over the first semiconductor film; etching the first semiconductor film and the gate insulating layer continuously with the first mask to form a patterned gate insulating film and a patterned first semiconductor film and to expose a portion of the gate electrode of the driving thin film transistor; removing the first mask; forming a protective layer over the patterned first semiconductor film after removing the first mask; forming a second semiconductor film including one conductivity type impurity; forming a source wiring and a drain wiring by a droplet discharging method, at the same time, and connecting one of the source wiring and the drain wiring to the gate electrode of the driving thin film transistor; and etching the second semiconductor film over the protective layer by the source wiring and the drain wiring as a second mask.
 6. The method of manufacturing a light-emitting device according to claim 4 or 5, wherein the step of forming the gate insulating film and the first semiconductor film over the base film is performed continuously without being exposed to an air.
 7. The method of manufacturing a light-emitting device according to any one of claims 1, 2, 4 and 5, wherein the gate insulating layer is formed by sequentially laminating a first silicon nitride film, a silicon oxide film and a second silicon nitride film.
 8. The method of manufacturing a light-emitting device according to any one of claims 1, 2, 4 and 5, wherein said substrate has an insulating surface.
 9. The method of manufacturing a light-emitting device according to any one of claims 1, 2, 4 and 5, wherein said substrate has a pretreated base surface. 